RealClimate attempts to explain cold winters and growing Antarctic sea ice

RealClimate: A conclusion of the 4th International Polar Year

The Antarctic sea-ice cover has increased on average in the last 30 years, but not everywhere. Both the general increase around East Antarctica and the large decrease off West Antarctica are attributed to the ozone hole and corresponding changes in the Southern Annular Mode (SAM, or the ‘Antarctic Oscillation’), though this probably doesn’t explain what is happening in winter. There is no clear polar amplification observed over Antarctica, such as seen as in the Arctic, and one explanation for this may be that the Antarctic continent has large ice sheets with enormous thermal inertia. But ice core data suggest that there have been amplification there in the past too. Nevertheless, the Arctic is characterized by a polar ocean with retreating sea-ice in the northern hemisphere. In both cases, changing air masses and the winds are important for inter-annual to inter-decadal variations, both in explaining cold winters over Eurasia and sea-ice around Antarctica.